In Perl you can just use a / as your path separator.
Why? Because Perl with automagically convert the /to
the correct path separator for the system it
is running on!

Unfortunately this is not true for Perl on (classic) MacOS.
On MacOS you can use / for manipulating @INC but
not for other file pathes. File::Spec which currently undergoes a major
rewrite to handle MacPerl and VMS in a better way is for sure
the way to go.
See also perlport